1. Field of the Invention
The present invention relates to a hard coat film. More particularly, the present invention relates to a hard coat film for protection of surfaces such as the surface of touch panels and displays, which suppresses attachment of finger prints on the surfaces during input operations by fingers and enables easy wiping out of the attached dirt such as finger prints while scratch resistance and abrasion resistance of conventional hard coat films are retained.
2. Description of Related Art
Transparent hard coat films have heretofore been used for protection of surfaces and prevention of glare and reflection in various image display apparatuses such as LCD (liquid crystal displays), touch panels, CRT (cathode ray tubes), PDP (plasma display panels), EL (electroluminescence displays) and optical disks.
Touch panels are used as the input apparatus for portable information terminals which are being widely used in recent years. The touch panel is an apparatus for inputting data by directly touching the surface of the display by a finger or a pen. About 90 percent of the entire touch panels are the touch panels of the resistance film type. The touch panel of the resistance film type has, in general, a structure in which a plastic substrate of the touching side which has a transparent electrically conductive (referred to as “conductive”, hereinafter) thin film such as a film of indium oxide doped with tin (ITO) deposited on one face of a transparent plastic substrate and a transparent substrate of the display side which has a transparent conductive thin film such as an ITO film deposited on one face of a transparent substrate material such as a glass plate are arranged with an insulating spacer placed between the two substrates in a manner such that the transparent conductive thin films in the two substrates are faced to each other. For the input operation, the face for input by touching (the face opposite to the face having the transparent conductive thin film) of the plastic substrate of the touching side is pressed by a pen or a finger and the transparent conductive thin film of the plastic substrate of the touching side and the transparent conductive thin film of the display side are brought into contact with each other.
However, the touch panel of the resistance film type has a problem in that the surface of the touching side is damaged and the transparent conductive thin film in the plastic substrate (the substrate material film) of the touching side is abraded, has cracks or separated from the substrate after the transparent conductive thin film of the plastic substrate of the touching side and the transparent conductive film of the transparent substrate of the display side are repeatedly brought into contact with each other. To overcome the above problem, it is wide conducted that hard coat layers of a synthetic resin are disposed on the surface of the touching side and between the transparent plastic substrate and the transparent conductive thin film.
To provide the property of preventing attachment of dirt and removing the attached dirt, it is frequently conducted that a silicone-based compound or a fluorine-based compound is added to conventional hard coat films having a hard coat layer which is formed and supported on a substrate film by curing by heating or with an ionizing radiation. However, the highly water-repellent surface obtained above does not always suppress the attachment of finger prints and the attached finger prints are more clearly visible. The above technology is useful only for suppressing attachment of materials used in the everyday living such as foods and cosmetics and allowing easy removal of these materials. The conventional hard coat films have a drawback in that finger prints are attached on the films after input operations with fingers and the attached finger prints are not easily wiped out.